1. Field of Invention
This invention relates to water-based coatings and caulking compositions for exterior surfaces which upon application quickly develop resistance to being washed out by inadvertent precipitation. These compositions comprise an aqueous dispersion of water-insoluble latex polymer prepared by emulsion polymerization, inorganic pigment dispersed with anionic polymer, and water-soluble salt of a multivalent complex ion having labile, volatile ligands, such as zinc ammonium complex ion.
This invention relates to water-based coatings and caulking compositions for exterior surfaces. Exterior coatings are exposed to the vicissitudes of weather from the very moment they are applied to protect an exterior surface. Water-based coatings are favored over solvent-borne coatings for a number of well known reasons. They offer ease of application, reduced toxic solvent emission, lower raw material and application costs, and easy cleanup of site and equipment. However, water-based coatings are particularly vulnerable to water damage during and immediately after application. A sudden summer shower can wash away or otherwise damage the result of many hours of labor and waste valuable materials.
2. Brief Description of the Prior Art
Exterior water-based coatings may be formulated using aqueous dispersions of water-insoluble polymer latex as binders. After application, the aqueous carrier evaporates, and the individual latex particles coalesce to form an integral film. Some applications require relatively thick coating films. For example, coatings for formed-in-place polyurethane foam which is used to thermally insulate and protect institutional, commercial and industrial roofs, are relatively thick, conventionally on the order of 20-40 mils (0.05-0.10 cm). These coatings are frequently referred to as "roof mastics." Roof mastics are often applied by spray techniques which allow many acres of coating to be applied during a single work period. Because they are applied as a thick coating, they lose water by evaporation relatively slowly in comparison with other polymer latex coatings products such as house paints. Thus, roof mastics are particularly vulnerable to being washed out by unanticipated precipitation. A substantial need exists for water-based roof mastics and other exterior water-based coatings products which resist washout immediately after application or shortly thereafter ("early" washout resistance).